Cathode

ABSTRACT

The present invention provides novel cathodes having a reduced resistivity and other improved electrical properties. Furthermore, this invention also presents methods of manufacturing novel electrochemical cells and novel cathodes. These novel cathodes comprise a silver material that is doped with a high valence early transition metal species

CROSS REFERENCE TO RELATED APPLICATION

This PCT application claims the benefit of U.S. provisional applicationSer. No. 61/386,194, filed on Sep. 24, 2010, hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

This invention is concerned with a new cathode formed by doping acathode material with a dopant that imparts the cathode with one or moreimproved properties over traditional cathodes.

BACKGROUND

When a traditional battery is discharged, the anode supplies positiveions to an electrolyte and electrons to an external circuit. The cathodeis typically an electronically conducting host into which positive ionsare inserted reversibly or irreversibly from the electrolyte as a guestspecies and are charge-compensated by electrons from the externalcircuit. A secondary battery, or cell, uses a reaction that can bereversed when current is applied to the battery, thus “recharging” thebattery. The chemical reactions at the anode and cathode of a secondarybattery must be reversible. On charge, the removal of electrons from thecathode by an external field releases positive ions back to theelectrolyte to restore the parent host structure, and the addition ofelectrons to the anode by the external field attractscharge-compensating positive ions back into the anode to restore it toits original composition.

Traditional electrode materials such as cathode active materials suffera number of drawbacks. For instance, many traditional cathodes possessan elevated impedance or internal resistance that negatively effectsbattery discharge, and thus, restricts battery performance. As manytraditional batteries progress through charge cycles, the deleteriouseffect of impedance causes an increasing hindrance on batteryperformance.

Thus, there is a need for electrode materials that have improvedproperties and can improve battery performance.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with ahigh valence dopant to give a doped silver material, wherein the dopantis present in a concentration of from about 0.01 mol % to about 10 mol%. In some embodiment, the high valence dopant is present in aconcentration of from about 0.10 mol % to about 5 mol %. For example,the high valence dopant is present in a concentration of from about 0.25mol % to about 2.5 mol %. In other examples, the high valence dopant ispresent in a concentration of from about 1 mol % to about 8 mol %.

In some embodiments of this aspect, the doped silver material comprisesa powder. For example, the doped silver material comprises a powder, andthe powder has a mean particle diameter of about 20 μm or less (e.g.,about 15 μm or less or about 10 μm or less). In other examples, thepowder has a mean particle diameter of about 7 μm or less.

In some embodiments of this aspect, the silver material furthercomprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi,AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂,FeO₃, Ag₂FeO₃, Ag₄FeO₄, or any combination thereof.

In other embodiments of this aspect, the cathode further comprises abinder such as PTFE or PVDF.

In some embodiments of this aspect, the high valence dopant comprises anelement (e.g., one or more elements selected) from groups 4-8 in theperiodic table of elements. In some instances, the high valence dopantcomprises Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.For example, the high valence dopant comprises an oxide or a hydroxideof Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof. Inother examples, the high valence dopant comprises an acetate, a formate,a sulfide, a sulfate, a nitrate, a nitride, an amide, a hydroxide, aperchlorate, a phosphate, a triflate, a silicide, or a carbonyl of Nb,Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof. And, in someexamples, the high valence dopant comprises a salt of Nb, Mn, Re, V, Ta,W, Mo, Cr, Fe, or any combination thereof. For instance, the highvalence dopant comprises Nb₂O₅, KMnO₄, KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃,CrO₃, MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O, or any combination thereof.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a doped silver material comprising adopant, wherein the dopant comprises Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe,or any combination thereof, and the dopant is present in a concentrationof from about 0.010 mol % to about 10 mol %. In some embodiments, thedopant is present in a concentration of from about 0.10 mol % to about 5mol %. For example, the dopant is present in a concentration of fromabout 0.25 mol % to about 2.5 mol %. In another example, the dopant ispresent in a concentration of from about 1 mol % to about 8 mol %.

In some embodiments of this aspect, the doped silver material comprisesa powder, such as any of the doped silver material powders describedherein. In other embodiments, the silver material comprises Ag, AgO,Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK,AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combinationthereof.

In other embodiments of this aspect, the cathode further comprises abinder such as PTFE or PVDF.

In some embodiments of this aspect, the dopant comprises any of the highvalence dopants or any combination of high valence dopants describedherein.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.01 mol % to about 10 mol % (e.g.,from about 0.10 mol % to about 5 mol %, from about 0.25 mol % to about2.5 mol %) of at lease one high valence dopant; and forming the dopedsilver powder into a cathode.

In some embodiments of this aspect, the doped silver powder is dopedwith from about 0.10 mol % to about 5 mol % of dopant. For example, thedoped silver powder comprises from about 0.25 mol % to about 2.5 mol %of dopant. In another example, the doped silver powder comprises fromabout 1 mol % to about 8 mol % of dopant. In some embodiments of thisaspect, the doped silver material comprises a powder, such as any of thedoped silver material powders described herein. And, in someembodiments, the doped silver powder comprises Ag, AgO, Ag₂O, Ag₂O₃,AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb,AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or any combination thereof. Forexample, the doped silver powder comprises AgO, Ag₂O, Ag₂O₃, or anycombination thereof.

Other embodiments of this aspect further comprise providing a bindersuch as PTFE or PVDF.

In some embodiments of this aspect, the dopant comprises any of the highvalence dopants or any combination of high valence dopants describedherein.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises a highvalence dopant, and the dopant is present in a sufficient concentrationto impart the cell with an actual capacity of at least about 60% of thecell's rated capacity over at least about 50 charge cycles (e.g., atleast 100 charge cycles, at least 150 charge cycles, at least 200 chargecycles, at least 250 charge cycles, at least 300 charge cycles, at least350 charge cycles, or at least 400 charge cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises a highvalence dopant, and the dopant is present in a sufficient concentrationto impart the cell with an actual capacity of at least about 70% of thecell's rated capacity over at least about 50 charge cycles (e.g., atleast 100 charge cycles, at least 150 charge cycles, at least 200 chargecycles, at least 250 charge cycles, at least 300 charge cycles, at least350 charge cycles, or at least 400 charge cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises at least onehigh valence dopant, and the dopant is present in a sufficientconcentration to impart the cell with an actual capacity of at leastabout 80% of the cell's rated capacity over at least about 50 chargecycles (e.g., at least 100 charge cycles, at least 150 charge cycles, atleast 200 charge cycles, at least 250 charge cycles, at least 300 chargecycles, at least 350 charge cycles, or at least 400 charge cycles).

In some embodiments of these aspects, the silver material comprises fromabout 0.01 mol % to about 10 wt % (e.g., from about 0.10 mol % to about5 mol %, from about 0.25 mol % to about 2.5 mol %) of at least one highvalence dopant. In other embodiments, the silver material comprises apowder as described herein.

In some embodiments of these aspects, the cathode, the anode, or bothcomprise a binder. For example, the cathode comprises a binder asdescribed herein. In other examples, the anode comprises a binder suchas PTFE or PVDF.

In some embodiments of these aspects, the cell further comprises anelectrolyte comprising NaOH, KOH, LiOH, RbOH, or a combination thereof.

In other embodiments of these aspects, the silver powder comprises Ag,AgO, Ag₂O, Ag₂O₃ Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa,AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃,Ag₄FeO₄, or any combination thereof. For example, the silver powdercomprises AgO, Ag₂O, Ag₂O₃, or any combination thereof. In otherexamples, the silver material comprises AgO. And, in some examples, thesilver material comprises Ag₂O.

In some embodiments of these aspects, the dopant comprises any of thehigh valence dopants or any combination of high valence dopantsdescribed herein.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver powder, as described herein,comprising from about 0.01 mol % to about 10 mol % (e.g., from about0.10 mol % to about 5 mol %, from about 0.25 mol % to about 2.5 mol %)of a high valence dopant; an anode comprising zinc; and an electrolytecomprising aqueous alkali hydroxide (e.g., LiOH, KOH, NaOH, or anycombination thereof). In some embodiments, the cathode, the anode, orboth comprise a binder, as described herein. And, in other embodiments,the electrolyte further comprises NaOH. In some embodiments, the silverpowder comprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa, AgOK,AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂,Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄, or any combination thereof. Forexample, the silver powder comprises AgO, Ag₂O, Ag₂O₃, or anycombination thereof. In some examples, the silver powder comprises AgO.In other examples, the silver powder comprises Ag₂O. In someembodiments, the dopant comprises any of the high valence dopants or anycombination of high valence dopants described herein.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a doped silver material comprising adopant, wherein the dopant comprises vanadium, niobium, tantalum, anyoxide thereof, any hydroxide thereof, or any combination thereof, andthe dopant is present in a concentration of from about 0.01 mol % toabout 10 mol % (e.g., from about 0.10 mol % to about 5 mol %, from about0.25 mol % to about 2.5 mol %).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an electrochemical cell of the presentinvention.

FIG. 2 is a graphical representation of comparative voltage data fromthe cycling of doped AgO cathode materials in 125 mAh test cells,wherein the solid line represents a cell having a cathode withoutdopant, the dashed line represents a cell having a cathode including anMn4+ dopant, the dash-dot line represents a cell having a cathodeincluding a Nb5+ dopant, and the dash-dot-dot line represents a cellhaving a cathode including a Ta5+ dopant.

FIG. 3 is a graphical representation of voltage data from a singlecharge cycle of doped AgO cathode materials in 125 mAh test cells,wherein the solid line represents a cell having a cathode withoutdopant, the dashed line represents a cell having a cathode including anMn4+ dopant, the dash-dot line represents a cell having a cathodeincluding a Nb5+ dopant, and the dash-dot-dot line represents a cellhaving a cathode including a Ta5+ dopant.

FIG. 4 is a graphical representation of comparative voltage data from asingle discharge of doped AgO cathode material in 125 mAh test cells,wherein the solid line represents a cell having a cathode withoutdopant, the dashed line represents a cell having a cathode including anMn4+ dopant, the dash-dot line represents a cell having a cathodeincluding a Nb5+ dopant, and the dash-dot-dot line represents a cellhaving a cathode including a Ta5+ dopant.

FIG. 5 is a graphical representation of comparative voltage data from asingle discharge of the doped AgO cathode material in 125 mAh testcells, wherein the solid line represents a cell having a cathode withoutdopant, the dashed line represents a cell having a cathode including anRe7+ dopant, the dash-dot line represents a cell having a cathodeincluding a V5+ dopant, and the dotted line represents a cell having acathode including a W6+ dopant.

FIG. 6 is a graphical representation of cycle-life data for a Nb5+ dopedAgO cathode material in a 125 mAh test cell.

FIG. 7 is a graphical representation of cycle-life data for a Mn4+ dopedAgO cathode material in a 125 mAh test cell.

FIG. 8 is a graphical representation of cycle-life data for a Re7+ dopedAgO cathode material in a 125 mAh test cell.

FIG. 9 is a graphical representation of cycle-life data for a Ta5+ dopedAgO cathode material in a 125 mAh test cell.

FIG. 10 is a graphical representation of cycle-life data for V6+ dopedAgO cathode materials in 125 mAh test cells.

FIG. 11 is a graphical representation of cycle-life data for W6+ dopedAgO cathode materials in 125 mAh test cells.

The figures are provided by way of example and are not intended to limitthe scope of the claimed invention.

DETAILED DESCRIPTION

The present invention provides cathodes, methods of making cathodes, andelectrochemical cells (e.g., batteries) that employ these cathodeshaving improved properties over traditional cathodes, methods, orelectrochemical cells.

I. DEFINITIONS

As used herein, the term “battery” encompasses electrical storagedevices comprising one electrochemical cell or a plurality ofelectrochemical cells. A “secondary battery” is rechargeable, whereas a“primary battery” is not rechargeable. For secondary batteries of thepresent invention, a battery anode is designated as the positiveelectrode during discharge, and as the negative electrode during charge.

As used herein, the terms “silver material” or “silver powder” refer toany silver compound such as Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH,AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂,AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄, hydrates thereof, orany combination thereof. Note that ‘hydrates’ of silver includehydroxides of silver. Silver materials may optionally compriseadditional additives such as MnO₂, CuO, AuO, or any combination thereof.Because it is believed that the coordination sphere surrounding a silveratom is dynamic during charging and discharging of the cell wherein thesilver serves as a cathode, or when the oxidation state of the silveratom is in a state of flux, it is intended that the term ‘silver powder’or ‘silver material’ encompass any of these silver oxides and hydrates(e.g., hydroxides). Terms ‘silver powder’ or ‘silver material’ alsoincludes any of the abovementioned species that are doped and/or coatedwith dopants and/or coatings that enhance one or more properties of thesilver. Example dopants and coatings are provided below. Note that theterm “oxide” used herein does not, in each instance, describe the numberof oxygen atoms present in the silver or silver material. One genericformula for silver oxide is AgO_(x)(OH)_(y)(H₂O)_(z), wherein x, y, andz are positive real numbers or zero, and at least one of x, y, or z isgreater than zero. In other examples, a silver oxide may have a chemicalformula of AgO, Ag₂O₃, Ag₂O, Ag₃O, or a combination thereof.Furthermore, silver can comprise a bulk material or silver can comprisea powder having any suitable mean particle diameter.

When used alone, the term “silver” refers to elemental silver.

As used herein, “high valence dopant” refers to a high valence earlytransition metal found in columns 4-8 of the periodic table of elements,i.e., metals of groups 4-8 in the periodic table of elements. In someexamples of high valence dopants, the early transition metal atomcomprising the dopant possesses an oxidation state between +4 and +7.Exemplary early transition metal elements comprising dopants includes V,Cr, Mn, Nb, Mo, Tc, Ta, W, Re, Fe, Ru, Os, Ti, Zr, Hf, or anycombination thereof. Moreover, high valence dopants also includeelemental, i.e., substantially purified, early transition metals, oxideforms of these early transition metals (e.g., naturally occurring oxideforms of these early transition metals), salts (e.g., Na salts, K salts,Li salts, Cs salts, Rb salts, or any combination thereof), or compounds(e.g., acetates, formates, sulfides, sulfates, nitrate, nitrides,amides, hydroxides, perchlorates, phosphates, triflates, silicides,carbonyls, or any combination thereof) that contain one or more of theseearly transition metals, or any combination thereof.

When referring to one or more group 4-8 early transition metals, theterm “oxide” refers to any oxide or hydroxide (e.g., hydrate) of thegroup 4-8 transition metal. For example, vanadium oxide includes anyoxide or hydroxide of vanadium (e.g., VO, V₂O₃, VO₂, V₆O₁₃, V₂O₅, or anycombination thereof). In another example, niobium oxide refers to anyoxide or any hydroxide of niobium (e.g., NbO, Nb₂O₃, NbO₂, Nb₂O₅, or anycombination thereof). In another example, tantalum oxide refers to anyoxide or any hydroxide of tantalum (e.g., TaO, Ta₂O₃, TaO₂, Ta₂O₅, orany combination thereof). In another example, “iron oxide” refers to anyoxide or any hydroxide of iron (e.g., FeO, Fe₂O₃, Fe₃O₄, Fe(OH)₂,Fe(OH)₃ FeOOH, Fe₅HO₈.4H₂O, or any combination thereof). In anotherexample, “tungsten oxide” refers to any oxide or any hydroxide oftungsten (e.g., W₂O₃, WO₂, WO₃, W₂O₃.2H₂O, or any combination thereof).In another example, ruthenium oxide refers to any oxide or any hydroxideof ruthenium (e.g., RuO₄, RuO₂, Ru(OH)₃, or any combination thereof). Inanother example, manganese oxide refers to any oxide or any hydroxide ofmanganese (e.g., MnO, Mn₃O₄, Mn₂O₃, MnO₂, Mn₂O₇, or any combinationthereof). And, in another example, molybdenum oxide refers to any oxideor any hydroxide of manganese (e.g., MoO₃, MoO₂, or any combinationthereof).

As used herein, a “group 5 element” refers to one or more of thechemical elements classified in the periodic table of elements undercolumn number 5. These elements include vanadium, niobium, tantalum anddubnium.

As used herein, the terms “divalent silver oxide” and “AgO” are usedinterchangeably.

As used herein, the term “alkaline battery” refers to a primary batteryor a secondary battery, wherein the primary or secondary batterycomprises an alkaline electrolyte.

As used herein, a “dopant” or “doping agent” refers to a chemicalcompound that is added to a substance in low concentrations (e.g., fromabout 0.1 mol % to about 10 mol %) in order to alter theoptical/electrical properties of the substance. For example, a dopantmay be added to a powder active material of a cathode to improve itselectronic properties (e.g., reduce its impedance and/or resistivity orimprove a cell's cycle life where the cathode is employed in said cell).In other examples, doping occurs when one or more atoms of a crystallattice of a bulk material is substituted with one or more atoms of adopant.

As used herein, an “electrolyte” refers to a substance that behaves asan electrically conductive medium. For example, the electrolytefacilitates the mobilization of electrons and cations in the cell.Electrolytes include mixtures of materials such as aqueous solutions ofalkaline agents. Some electrolytes also comprise additives such asbuffers. For example, an electrolyte comprises a buffer comprising aborate or a phosphate. Example electrolytes include, without limitation,aqueous KOH, aqueous NaOH, a mixture of aqueous NaOH and KOH, or theliquid mixture of KOH, NaOH, or a combination thereof in a polymer.

As used herein, “alkaline agent” refers to a base or ionic salt of analkali metal (e.g., an aqueous hydroxide of an alkali metal).Furthermore, an alkaline agent forms hydroxide ions when dissolved inwater or other polar solvents. Example alkaline electrolytes includewithout limitation LiOH, NaOH, KOH, CsOH, RbOH, or combinations thereof.Electrolytes can optionally include other salts to modify the totalionic strength of the electrolyte, for example KF, K₃PO₄, or Ca(OH)₂.

A “cycle” or “charge cycle” refers to a consecutive charge and dischargeof a cell or a consecutive discharge and charge of a cell, either ofwhich includes the duration between the consecutive charge and dischargeor the duration between the consecutive discharge and charge. Forexample, a cell undergoes one cycle when, freshly prepared, it isdischarged to about 100% of its DOD and re-charged to about 100% of itsstate of charge (SOC). In another example, a freshly prepared cellundergoes 2 cycles when the cell is:

-   -   1) Cycle 1: discharged to about 100% of its DOD and re-charged        to about 100% SOC; immediately followed by    -   2) Cycle 2: a second discharge to about 100% of its DOD and        re-charged to about 100% SOC.

It is noted that this process may be repeated to subject a cell to asmany cycles as is desired or practical.

As used herein, “Ah” refers to Ampere (Amp) Hour and is a scientificunit denoting the capacity of a battery or electrochemical cell. Aderivative unit, “mAh” represents a milliamp hour and is 1/1000 of anAh.

As used herein, “depth of discharge” and “DOD” are used interchangeablyto refer to the measure of how much energy has been withdrawn from abattery or cell, often expressed as a percentage of capacity, e.g.,rated capacity. For example, a 100 Ah battery from which 30 Ah has beenwithdrawn has undergone a 30% depth of discharge (DOD).

As used herein, “state of charge” and “SOC” and used interchangeably torefer to the available capacity remaining in a battery, expressed as apercentage of the cell or battery's rated capacity.

For convenience, the polymer name “polyvinylidene fluoride” and itscorresponding initials “PVDF” are used interchangeably to distinguishpolymers, solutions for preparing polymers, and polymer coatings. Use ofthese names and initials in no way implies the absence of otherconstituents. These adjectives also encompass substituted andco-polymerized polymers. A substituted polymer denotes one for which asubstituent group, a methyl group, for example, replaces a hydrogen orfluorine on the polymer backbone.

For convenience, the polymer name “polytetrafluoroethylene” and itscorresponding initials “PTFE” are used interchangeably to distinguishpolymers, solutions for preparing polymers, and polymer coatings. Use ofthese names and initials in no way implies the absence of otherconstituents. These terms also encompass substituted and co-polymerizedpolymers. A substituted polymer denotes one for which a substituentgroup, a methyl group, for example, replaces a hydrogen on the polymerbackbone.

As used herein, “organometallic complex” and “complex” refer tocomplexes or compounds having bonds or binding interactions (e.g.,electrostatic interactions) between a metal (e.g., lead or silver) andone or more organic ligands (e.g., nitrate or acetate). Organic ligandsoften bind the metal through a heteroatom such as oxygen or nitrogen.

Batteries and battery electrodes are denoted with respect to the activematerials in the fully-charged state. For example, a zinc-silver batterycomprises an anode comprising zinc and a cathode comprising a silverpowder (e.g., Ag₂O₃). Nonetheless, more than one species is present at abattery electrode under most conditions. For example, a zinc electrodegenerally comprises zinc metal and zinc oxide (except when fullycharged), and a silver powder electrode usually comprises AgO, Ag₂O₃and/or Ag₂O and silver metal (except when fully discharged).

As used herein, “maximum voltage” or “rated voltage” refers to themaximum voltage an electrochemical cell can be charged withoutinterfering with the cell's intended utility. For example, in severalzinc-silver electrochemical cells that are useful in portable electronicdevices, the maximum voltage is less than about 2.5 V (e.g., about 2.3 Vor less, or about 2.0 V). In other batteries, such as lithium ionbatteries that are useful in portable electronic devices, the maximumvoltage is less than about 15.0 V (e.g., less than about 13.0 V, orabout 12.6 V or less). The maximum voltage for a battery can varydepending on the number of charge cycles constituting the battery'suseful life, the shelf-life of the battery, the power demands of thebattery, the configuration of the electrodes in the battery, and theamount of active materials used in the battery.

As used herein, an “anode” is an electrode through which (positive)electric current flows into a polarized electrical device. In a batteryor galvanic cell, the anode is the negative electrode from whichelectrons flow during the discharging phase in the battery. The anode isalso the electrode that undergoes chemical oxidation during thedischarging phase. However, in secondary, or rechargeable, cells, theanode is the electrode that undergoes chemical reduction during thecell's charging phase. Anodes are formed from electrically conductive orsemiconductive materials, e.g., metals, metal oxides, metal alloys,metal composites, semiconductors, or the like. Common anode materialsinclude Si, Sn, Al, Ti, Mg, Ga, Fe, Bi, Zn, Sb, Ni, Pb, Li, Zr, Hg, Cd,Cu, LiC₆, mischmetals, alloys thereof, oxides thereof, or compositesthereof. Anode materials such as zinc may even be sintered.

Anodes may have many configurations. For example, an anode may beconfigured from a conductive mesh or grid that is coated with one ormore anode materials. In another example, an anode may be a solid sheetor bar of anode material.

As used herein, a “cathode” is an electrode from which (positive)electric current flows out of a polarized electrical device. In abattery or galvanic cell, the cathode is the positive electrode intowhich electrons flow during the discharging phase in the battery. Thecathode is also the electrode that undergoes chemical reduction duringthe discharging phase. However, in secondary or rechargeable cells, thecathode is the electrode that undergoes chemical oxidation during thecell's charging phase. Cathodes are formed from electrically conductiveor semiconductive materials, e.g., metals, metal oxides, metal alloys,metal composites, semiconductors, or the like. Common cathode materialsinclude Ag, AgO, Ag₂O₃, Ag₂O, HgO, Hg₂O, CuO, CdO, NiOOH, Pb₂O₄, PbO₂,LiFePO₄, Li₃V₂(PO₄)₃, V₆O₁₃, V₂O₅, Fe₃O₄, Fe₂O₃, MnO₂, LiCoO₂, LiNiO₂,LiMn₂O₄, or composites thereof. Cathode materials such as Ag, AgO, Ag₂O₃may even be sintered.

Cathodes may also have many configurations. For example, a cathode maybe configured from a conductive mesh that is coated with one or morecathode materials. In another example, a cathode may be a solid sheet orbar of cathode material.

As used herein, the term “electronic device” is any device that ispowered by electricity. For example, and electronic device can include aportable computer, a portable music player, a cellular phone, a portablevideo player, hearing aid, medical device, or any device that combinesthe operational features thereof.

As used herein, the term “cycle life” is the maximum number of times asecondary battery can be cycled while retaining a capacity useful forthe battery's intended use (e.g., the number of times a cell may becycled until the cell's 100% SOC, i.e., its actual capacity, is lessthan 90% of its rated capacity (e.g., less than 85% of its ratedcapacity, about 90% of its rated capacity, or about 80% of its ratedcapacity). In some instances, ‘cycle life’ is the number of times asecondary battery or cell can be cycled until the cell's 100% SOC is atleast about 60 percent of its rated capacity (e.g., at least about 70percent of its rated capacity, at least about 80 percent of its ratedcapacity, at least 90 percent of its rated capacity, at least 95 percentof its rated capacity, about 90% of its rated capacity, or about 80% ofits rated capacity).

As used herein, the symbol “M” denotes molar concentration.

Batteries and battery electrodes are denoted with respect to the activematerials in the fully-charged state. For example, a zinc-silver batterycomprises an anode comprising zinc and a cathode comprising a silverpowder (e.g., AgO or Ag₂O₃). Nonetheless, more than one species ispresent at a battery electrode under most conditions. For example, azinc electrode generally comprises zinc metal and zinc oxide (exceptwhen fully charged), and a silver powder electrode usually comprisessilver powder (e.g., AgO, Ag₂O₃ and/or Ag₂O and silver metal (exceptwhen fully discharged).

As used herein, the term “oxide” applied to alkaline batteries andalkaline battery electrodes encompasses corresponding “hydroxide”species and “hydrate” species, which are typically present, at leastunder some conditions.

As used herein, the term, “powder” refers to a granular solid composedof a plurality of fine particles. In some instances, a powder's granulesmay flow freely when shaken or tilted, and in other instances, apowder's granules may cohere together, for example, in powderscomprising a binder.

As used herein, the term, “mean diameter” or “mean particle diameter”refers to the diameter of a sphere that has the same volume/surface arearatio as a particle of interest.

As used herein, the terms “substantially stable” or “substantiallyinert” refer to a compound or component that remains substantiallychemically unchanged in the presence of an alkaline electrolyte (e.g.,potassium hydroxide) and/or in the presence of an oxidizing agent (e.g.,silver ions present in the cathode or dissolved in the electrolyte).

As used herein, “charge profile” refers to a graph of an electrochemicalcell's voltage or capacity with time or cycle number. A charge profilecan be superimposed on other graphs such as those including data pointssuch as charge cycles or the like.

As used herein, “resistivity” or “impedance” refers to the internalresistance of a cathode in an electrochemical cell. This property istypically expressed in units of Ohms or micro-Ohms.

As used herein, the terms “first” and/or “second” do not refer to orderor denote relative positions in space or time, but these terms are usedto distinguish between two different elements or components. Forexample, a first separator does not necessarily proceed a secondseparator in time or space; however, the first separator is not thesecond separator and vice versa. Although it is possible for a firstseparator to precede a second separator in space or time, it is equallypossible that a second separator precedes a first separator in space ortime.

As used herein, the term “nanometer” and “nm” are used interchangeablyand refer to a unit of measure equaling 1×10⁻⁹ meters.

As used herein, the term “cathode active material” or “cathode” refer toa composition that includes silver, as described above (e.g., dopedsilver, coated silver, silver that is doped or coated, or anycombination thereof).

As used herein, the term “capacity” refers to the mathematical productof a cell's discharge current and the time (in hours) during which thecurrent is discharged until the cell reaches its terminal voltage.

Similarly, the term “actual capacity” refers to the capacity of thebattery or cell when the cell has 100% SOC. In general terms, thecapacity of a cell/battery is the amount of charge available expressedin ampere-hours (Ah). An ampere is the unit of measurement used forelectrical current and is defined as a coulomb of charge passing throughan electrical conductor in one second. The capacity of a cell or batteryis related to the quantity of active materials present, the amount ofelectrolyte present, and the surface area of the electrodes. Thecapacity of a battery/cell can be measured by discharging at a constantcurrent until it reaches its terminal voltage, which depends on thecell's intended usage.

A cell's “rated capacity” is the capacity that a cell shouldtheoretically discharge at 100% SOC based on the amounts of electrodematerials present in the cell, the amount of electrolyte present in thecell, the surface area of the electrodes, and the cell's intended usage.For many types of cells, industry standards establish a cell's ratedcapacity, which is based on the cell's intended usage.

II. CATHODES

One aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with atleast one high valence dopant to give a doped silver material, whereinthe dopant is present in a concentration of from about 0.01 mol % toabout 10 mol % (e.g., from about 0.10 mol % to about 5 mol %, from about0.20 mol % to about 4 mol %, from about 0.25 mol % to about 5 mol %, orfrom about 1 mol % to about 8 mol %).

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with atleast one high valence dopant to give a doped silver material, whereinthe dopant is present in a concentration of from about 50 ppm to about1000 ppm.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with atleast one high valence dopant to give a doped silver material, whereinthe dopant is present in a concentration of from about 500 ppm to about5000 ppm.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped with adopant comprising an early transition metal element of any of groups 4-8in the periodic table of elements, wherein the dopant is present in aconcentration of from about 0.01 mol % to about 10 mol % (e.g., fromabout 0.10 mol % to about 5 mol %, from about 0.20 mol % to about 4 mol%, from about 0.25 mol % to about 5 mol %, or from about 1 mol % toabout 8 mol %). For example, the high valence dopant comprises Nb, Mn,Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof. In anotherexample, the high valence dopant comprises an oxide or a hydroxide ofNb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof. In someexamples, the high valence dopant comprises an acetate, a formate, asulfide, a sulfate, a nitrate, a nitride, an amide, a hydroxide, aperchlorate, a phosphate, a triflate, a silicide, a carbonate, or acarbonyl of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combinationthereof. In some examples, the high valence dopant comprises a salt ofNb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof. In otherexamples, the high valence dopant comprises Nb₂O₅, KMnO₄, KReO₄, V₂O₅,Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O, or anycombination thereof.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped withvanadium, niobium, tantalum, or any combination thereof, to give a dopedsilver material, wherein the dopant is present in a concentration offrom about 0.01 mol % to about 10 mol % (e.g., from about 0.10 mol % toabout 5 mol %, from about 0.20 mol % to about 4 mol %, from about 0.25mol % to about 5 mol %, or from about 1 mol % to about 8 mol %).

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped withniobium, to give a doped silver material, wherein the dopant is presentin a concentration of from about 0.01 mol % to about 10 mol % (e.g.,from about 0.10 mol % to about 5 mol %, from about 0.20 mol % to about 4mol %, from about 0.25 mol % to about 5 mol %, or from about 1 mol % toabout 8 mol %).

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material that is doped withmanganese (e.g., MnO₂), to give a doped silver material, wherein thedopant is present in a concentration of from about 0.01 mol % to about10 mol % (e.g., from about 0.10 mol % to about 5 mol %, from about 0.20mol % to about 4 mol %, from about 0.25 mol % to about 5 mol %, or fromabout 1 mol % to about 8 mol %) by weight of the doped silver material.

In some embodiments above, the doped silver material comprises fromabout 0.5 mol % to about 5 mol % of a high valence dopant. In otherembodiments above, the doped silver material comprises from about 1 mol% to about 8 mol % of high valence dopant. In other embodiments, thesilver material of the cathode comprises a powder. For instance, thepowder has a mean particle diameter of about 20 μm or less (e.g., 15 μmor less, or 10 μm or less). In other instances, the powder has a meanparticle diameter of about 15 μm or less (e.g., 10 μm or less). In otherinstances, the powder has a mean particle diameter of about 7 μm orless. In other embodiments, the doped silver material comprises Ag, AgO,Ag₂O, Ag₂O₃, AgOH, AgOOH, AgONa, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, or anycombination thereof. In some embodiments, the cathode further comprisesa binder. For example, the cathode comprises a binder and the bindercomprises PTFE or PVDF.

One aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver material comprising a dopant,as described above, wherein the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 50 Ohm·cm orless. In several embodiments, the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 40 Ohm·cm orless. In several embodiments, the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 35 Ohm·cm orless. In several embodiments, the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 30 Ohm·cm orless (e.g., about 25 Ohm·cm or less, about 20 Ohm·cm or less, or about12 Ohm·cm or less).

In one embodiment, the cathode comprises from about 0.01 mol % to about10 mol % of dopant. For example, the cathode comprises from about 0.25mol % to about 5 mol % of dopant. In other examples, the cathodecomprises from about 0.5 mol % to about 2.5 mol % of dopant. And, insome examples, the cathode comprises from about 0.75 mol % to about 2.0mol % of dopant.

Also, cathodes of the present invention comprise a silver material. Thesilver material includes bulk material that may be doped with a dopant,as provided herein, or the silver material may comprise a powder. Inembodiments, where the silver material comprises a powder, the powdermay be doped or coated (e.g., a plurality of the granules of silvermaterial comprising the powder are doped with a dopant). Furthermore,the powder may undergo further processing (e.g., hot pressing, bindingwith a polymer, granulation, or the like) to generate a silver bulkmaterial or silver-polymer material that is useful in cathodes of thepresent invention.

In another embodiment, the cathode comprises a silver powder that isdoped with a dopant, wherein the doped silver powder has a mean particlediameter of about 15 μm or less. For example, the doped silver powderhas a mean particle diameter of about 10 μm or less. In other examples,the doped silver powder has a mean particle diameter of about 7 μm orless. And, in other examples, the doped silver powder has a meanparticle diameter of about 5 μm or less.

In several embodiments, the cathodes comprise silver material (e.g.,silver powder) and the silver material comprises Ag, AgO, Ag₂O, Ag₂O₃,Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi,AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄,hydrates thereof, or any combination thereof. For example, the cathodecomprises silver material (e.g., silver powder), which comprises AgO. Inanother example, the silver powder comprises Ag₂O₃. In another example,the silver powder comprises Ag₂O.

Cathodes of the present invention can optionally comprise additives suchas binders, or other additives to improve one or more features of thecathode. In one example, the cathode comprises a binder. Suitablebinders include any binder that is substantially inert to the silveroxide powder or doped silver oxide powder. For example, the bindercomprises PTFE or PVDF.

In another embodiment, a cathode for use in an electrochemical cellcomprising a silver powder doped with a sufficient concentration of highvalence dopant such that cathode has a resistivity of about 30 Ohm·cm orless; and the doped silver powder has a mean particle diameter of about7 μm or less.

In another embodiment, a cathode for use in an electrochemical cellcomprising a silver powder doped with a sufficient concentration of highvalence dopant such that cathode has a resistivity of about 30 Ohm·cm orless; the doped silver powder has a mean particle diameter of about 7 μmor less; and the high valence dopant comprises V, Cr, Mn, Nb, Mo, Tc,Ta, W, Re, Fe, Ru, Os, Ti, Zr, Hf, or any combination thereof (e.g., Nb,Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof (e.g., Nb₂O₅,KMnO₄, KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂, Fe₂O₃,Fe(NO₃)₃.9H₂O, or any combination thereof)).

In another embodiment, a cathode comprises a silver powder that is dopedwith a sufficient amount of V, Cr, Mn, Nb, Mo, Tc, Ta, W, Re, Fe, Ru,Os, Ti, Zr, Hf, or any combination thereof (e.g., Nb, Mn, Re, V, Ta, W,Mo, Cr, Fe, or any combination thereof. (e.g., Nb₂O₅, KMnO₄, KReO₄,V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O, or anycombination thereof)), any oxide thereof, any hydroxide thereof, or anycombination thereof to provide a resistivity of about 30 Ohm·cm or lessand has a mean particle diameter of about 7 μm or less, wherein thesilver powder comprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa,AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂,AgMnO₂, Ag(OH)₂, RO₃, Ag₂FeO₃, Ag₄FeO₄, hydrates thereof, or anycombination thereof.

As noted above, cathodes of the present invention can optionallycomprise additives such as binders, current collectors, or the like. Inseveral examples, the cathode of the present invention comprises abinder. For instance, the cathode comprises a binder, and the bindercomprises PTFE, PVDF or a PVDF copolymer (e.g., a hexafluoropropyleneco-polymer, (PVDF-co-HFP)), carboxymethylcellulose (CMC),polyvinylpyrrolidone (PVP), polyacrylic acid (PAA), or any copolymerthereof.

Furthermore cathodes of the present invention comprise silver powder.Silver powder includes Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa,AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂,AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄, hydrates thereof, or anycombination thereof.

Another aspect of the present invention provides a cathode for use in anelectrochemical cell comprising a silver powder comprising a dopant, asdescribed above, and the dopant is present in a sufficient concentrationsuch that cathode has a resistivity of about 40 Ohm·cm or less.

In one embodiment, the cathode comprises from about 0.01 mol % to about10 mol % of dopant, i.e., niobium. For example, the cathode comprisesfrom about 0.25 mol % to about 5 mol % of dopant, i.e., niobium. Inother examples, the cathode comprises from about 1 mol % to about 8 mol% of dopant, i.e., niobium.

In another embodiment, the cathode comprises a doped silver powder thathas a mean particle diameter of about 20 μm or less. In someembodiments, the cathode comprises a doped silver powder that has a meanparticle diameter of about 15 μm or less. For example, the doped silverpowder has a mean particle diameter of about 7 μm or less.

In another embodiment, the dopant is present in a sufficientconcentration such that cathode has a resistivity of about 30 Ohm·cm orless.

Cathodes of the present invention comprise silver oxide. For example,the cathode comprises silver powder comprising Ag, AgO, Ag₂O, Ag₂O₃,Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi,AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄,hydrates thereof, or any combination thereof. In one example, the silverpowder comprises Ag₂O₃. In another example, the silver powder comprisesAgO.

Cathodes of the present invention can optionally comprise additives suchas binders, or other additives to improve one or more features of thecathode. In one example, the cathode comprises a binder. Suitablebinders include any binder that is substantially inert to the silveroxide powder or doped silver oxide powder. For example, the bindercomprises PTFE or PVDF.

In another embodiment, a cathode for use in an electrochemical cellcomprising a doped silver powder comprising a dopant, wherein the dopantcomprises niobium or an oxide thereof, and the dopant is present in asufficient concentration such that cathode has a resistivity of about 30Ohm·cm or less; and the doped silver oxide powder has a mean particlediameter of about 5 μm or less.

In another embodiment, a cathode comprises a silver powder that is dopedwith a sufficient amount of niobium or an oxide thereof to provide aresistivity of about 30 Ohm·cm or less and has a mean particle diameterof about 7 μm or less, wherein the silver powder comprises AgO, Ag₂O,Ag₂O₃, or any combination thereof.

As noted above, cathodes of the present invention can optionallycomprise additives such as binders, current collectors, or the like. Inseveral examples, the cathode of the present invention comprises abinder. For instance, the cathode comprises a binder, and the bindercomprises PTFE, PVDF (e.g., PVDF-co-HFP), CMC, PVP, PAA, or anycopolymer thereof.

In some embodiments, the cathode of the present invention furthercomprises one or more additional additives such as nanomaterials (e.g.,nano-sized SiO₂, nano-sized ZnO, nano-sized ZrO₂, or any combinationthereof), trivalent material (e.g., dopants comprising a compound ofgroup 13 in the periodic table, including any oxide, any hydroxide, anysalt, or any combination thereof), silicates, or any combinationthereof. In some instances, the cathode comprises a physical mixture ofany combination of these additives along with the silver material. Inother instances, the silver is doped with any combination of theseadditives.

III. METHODS

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.01 mol % to about 10 mol % (e.g.,from about 0.10 mol % to about 5 mol %, from about 0.25 mol % to about2.5 mol %) of a high valence dopant by weight of the cathode to give adoped silver powder; and forming the doped silver powder into a cathode.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.01 mol % to about 10 mol % (e.g.,from about 0.10 mol % to about 5 mol %, from about 0.25 mol % to about2.5 mol %) of a high valence dopant comprising at least one elementselected from any of groups 4-8 in the periodic table of elements; andforming the doped silver powder into a cathode. In some examples, thehigh valence dopant comprises Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or anycombination thereof. In another example, the high valence dopantcomprises an oxide or a hydroxide of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe,or any combination thereof. In some examples, the high valence dopantcomprises any acetate, any formate, any sulfide, any sulfate, anynitrate, any nitride, any amide, any hydroxide, any perchlorate, anyphosphate, any triflate, any silicide, or any carbonyl of Nb, Mn, Re, V,Ta, W, Mo, Cr, Fe, or any combination thereof. In some examples, thehigh valence dopant comprises any salt of Nb, Mn, Re, V, Ta, W, Mo, Cr,Fe, or any combination thereof. In other examples, the high valencedopant comprises Nb₂O₅, KMnO₄, KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃,MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O, or any combination thereof.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.010 mol % to about 10 mol %(e.g., from about 0.10 mol % to about 5 mol %, from about 0.25 mol % toabout 2.5 mol %) of a high valence dopant comprising vanadium, niobium,any oxide thereof, any hydroxide thereof, or any combination thereof byweight of the doped silver powder to give a doped silver powder; andforming the doped silver powder into a cathode.

Another aspect of the present invention provides a method of producing acathode for use in an electrochemical cell comprising providing a silverpowder that is doped with from about 0.01 mol % to about 10 mol % (e.g.,from about 0.10 mol % to about 5 mol %, from about 0.25 mol % to about2.5 mol %) of a high valence dopant comprising Nb, Mn, Re, V, Ta, W, Mo,Cr, Fe, or any combination thereof, to give a doped silver powder; andforming the doped silver powder into a cathode.

In some embodiments, the doped silver powder has a mean particlediameter of about 20 μm or less. And, in some embodiments, the dopedsilver powder has a mean particle diameter of about 15 μm or less. Forinstance, the doped silver powder has a mean particle diameter of about5 μm or less. In some embodiments of the methods above, the silverpowder comprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa, AgOK,AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂,Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄, any hydrate thereof, or any combinationthereof. In others, the silver powder comprises AgO, Ag₂O, Ag₂O₃, or anycombination thereof. In other embodiments of the methods above, the highvalence dopant comprises at least one element of any of groups 4-8 inthe periodic table of elements (e.g., Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe,or any combination thereof). In another example, the high valence dopantcomprises an oxide or a hydroxide of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe,or any combination thereof. In some examples, the high valence dopantcomprises an acetate, a formate, a sulfide, a sulfate, a nitrate, anitride, an amide, a hydroxide, a perchlorate, a phosphate, a triflate,a silicide, or a carbonyl of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or anycombination thereof. In some examples, the high valence dopant comprisesa salt of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.In other examples, the high valence dopant comprises Nb₂O₅, KMnO₄,KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O,or any combination thereof. For example, the dopant comprises vanadium,niobium, any oxide thereof, any hydroxide thereof, or any combinationthereof. In other examples, the dopant comprises niobium, tanatalum, anyoxide thereof, any hydroxide thereof, or any combination thereof.

Some embodiments of the methods above further comprise the step ofproviding a binder. For example, the method further includes providing abinder and the binder comprises PTFE or PVDF.

Another aspect of the present invention provides methods ofmanufacturing a cathode comprising providing a silver powder; and dopingthe silver powder (e.g., Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH,AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂,AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄₂, hydrates thereof, orany combination thereof) with a sufficient amount of high valence dopantsuch that cathode has a resistivity of about 50 Ohm·cm or less, whereinthe dopant comprises vanadium, niobium, tantalum, iron, tungsten,ruthenium, manganese, molybdenum, any oxide thereof, any hydroxidethereof, or any combination thereof.

In several embodiments, the silver powder is doped with a sufficientamount of dopant such that the cathode has a resistivity of about 40Ohm·cm or less. For example, the silver powder is doped with asufficient amount of dopant such that the cathode has a resistivity ofabout 35 Ohm·cm or less. Or, the silver powder is doped with asufficient amount of dopant such that the cathode has a resistivity ofabout 30 Ohm·cm or less.

In some methods, the silver powder is doped with from about 0.01 mol %to about 10 mol % (e.g., from about 0.10 mol % to about 5 mol %, fromabout 0.25 mol % to about 2.5 mol %, or from about 1 mol % to about 8mol %) of any of high valence dopants mentioned herein. For example, thesilver powder is doped with from about 1 mol % to about 8 mol % of highvalence dopant.

In other methods, the doped silver powder has a mean particle diameterof about 15 μm or less. For example, the doped silver powder has a meanparticle diameter of about 7 μm or less.

In some alternative methods, the silver powder comprises AgO. Or, thesilver oxide powder comprises Ag₂O₃.

Methods of the present invention can optionally include providingcathode additives. One example method includes further comprisingproviding a binder. Suitable binders include any of those mentionedherein. For example, the binder comprises PTFE or PVDF.

It is noted that in some methods, provided above, the dopant may possessa high valency when it is incorporated with the silver powder and/orsilver material. In other methods, the dopant (e.g., a manganese dopant(e.g., MnO₂)) is added to the silver powder and/or silver material andthe mixture of the silver and the dopant is oxidized (e.g., withpersulfate) to impart the dopant with the claimed valence.

Some methods of the present invention optionally include the step ofadding one or more additional additives to the cathode such asnanomaterials (e.g., nano-sized SiO₂, nano-sized ZnO, nano-sized ZrO₂,or any combination thereof), trivalent materials (e.g., materials and/ordopants comprising a group 13 element, including any oxide, anyhydroxide, any salt, or any combination thereof), silicates, or anycombination thereof. These additives may be added, in any combination,to the cathode to generate a physical mixture with the silver material,or the silver material may be doped with any combination of theseadditives.

Another aspect of the present invention provides methods ofmanufacturing a cathode comprising providing a silver powder; and dopingthe silver powder with a sufficient amount of dopant such that cathodehas a resistivity of about 30 Ohm·cm or less, wherein the dopantcomprises niobium or an oxide thereof.

Another aspect of the present invention provides methods ofmanufacturing a cathode comprising providing a silver powder; and dopingthe silver powder with a sufficient amount of dopant such that cathodehas a resistivity of about 30 Ohm·cm or less, wherein the dopantcomprises manganese or an oxide thereof.

In some alternative methods, the silver powder comprises AgO. Or, thesilver oxide powder comprises Ag₂O₃.

IV. ELECTROCHEMICAL CELLS

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a highvalence dopant; and an anode comprising zinc, wherein the high valencedopant is present in a sufficient concentration to impart the cell withan actual capacity of at least about 60% (e.g., at least about 70%, orat least about 80%) of the cell's rated capacity over at least 50 chargecycles (e.g., at least 100 charge cycles, at least 150 charge cycles, atleast 200 charge cycles, at least 250 charge cycles, at least 300 chargecycles, or at least 400 charge cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a highvalence dopant; and an anode comprising zinc, wherein the high valencedopant is present in a sufficient concentration to impart the cell withan actual capacity of at least about 70% of the cell's rated capacityover at least about 50 charge cycles (e.g., at least 100 charge cycles,at least 150 charge cycles, at least 200 charge cycles, at least 250charge cycles, at least 300 charge cycles, or at least 400 chargecycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a highvalence dopant; and an anode comprising zinc, wherein the high valencedopant comprises at least one element selected from any of groups 4-8 inthe periodic table of elements (e.g., Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe,or any combination thereof), and the high valence dopant is present in asufficient concentration to impart the cell with an actual capacity ofat least about 80% (e.g., at least about 85%, or at least about 90%) ofthe cell's rated capacity over at least 50 charge cycles (e.g., at least100 charge cycles, at least 150 charge cycles, at least 200 chargecycles, at least 250 charge cycles, at least 300 charge cycles, or atleast 400 charge cycles). In some examples, the high valence dopantcomprises an oxide or a hydroxide of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe,or any combination thereof. In some examples, the high valence dopantcomprises an acetate, a formate, a sulfide, a sulfate, a nitrate, anitride, an amide, a hydroxide, a perchlorate, a phosphate, a triflate,a silicide, a carbonate, or a carbonyl of Nb, Mn, Re, V, Ta, W, Mo, Cr,Fe, or any combination thereof. In some examples, the high valencedopant comprises a salt of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or anycombination thereof. In other examples, the high valence dopantcomprises Nb₂O₅, KMnO₄, KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂,Fe₂O₃, Fe(NO₃)₃.9H₂O, or any combination thereof.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a highvalence dopant; and an anode comprising zinc, wherein the high valencedopant comprises at least one Group 5 element (e.g., vanadium, niobium,tantalum, or any combination thereof), and the high valence dopant ispresent in a sufficient concentration to impart the cell with an actualcapacity of at least about 60% (e.g., at least about 70%, or at leastabout 80%) of the cell's rated capacity over at least 50 charge cycles(e.g., at least 100 charge cycles, at least 150 charge cycles, at least200 charge cycles, at least 250 charge cycles, at least 300 chargecycles, or at least 400 charge cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a highvalence dopant; and an anode comprising zinc, wherein the high valencedopant comprises vanadium, niobium, any oxide thereof, any hydroxidethereof, or any combination thereof, and the dopant is present in asufficient concentration to impart the cell with an actual capacity ofat least about 70% (e.g., at least about 85%, or at least about 90%) ofthe cell's rated capacity over at least 50 charge cycles (e.g., at least100 charge cycles, at least 150 charge cycles, at least 200 chargecycles, at least 250 charge cycles, at least 300 charge cycles, or atleast 400 charge cycles).

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising a silver material comprising a highvalence dopant; and an anode comprising zinc, wherein the high valencedopant comprises iron, tungsten, ruthenium, manganese, molybdenum, anyoxide thereof, any hydroxide thereof, or any combination thereof, andthe dopant is present in a sufficient concentration to impart the cellwith an actual capacity of at least about 70% (e.g., at least about 85%,or at least about 90%) of the cell's rated capacity over at least 50charge cycles (e.g., at least 100 charge cycles, at least 150 chargecycles, at least 200 charge cycles, at least 250 charge cycles, at least300 charge cycles, or at least 400 charge cycles).

In some embodiments, the silver material comprises from about 0.01 mol %to about 10 wt % of high valence dopant. In some embodiments, the silvermaterial comprises from about 0.10 mol % to about 5 wt % of high valencedopant. In some embodiments, the silver material comprises from about0.25 mol % to about 2.5 mol % of high valence dopant. In someembodiments, the silver material comprises from about 0.10 mol % toabout 2.5 mol % of high valence dopant, such as any of those describedherein.

In some embodiments, the doped silver material comprises a powder. Forinstance, the doped silver material comprises a powder and the powderhas a mean particle diameter of about 20 μm or less (e.g., 15 μm orless, 10 μm or less). In other instances, the doped powder has a meanparticle diameter of about 7 μm or less. In other embodiments, the dopedsilver powder comprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa,AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂,AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄, hydrates thereof, or anycombination thereof. In several embodiments, the silver powder comprisesAgO, Ag₂O, Ag₂O₃, or any combination thereof. For instance, the silvermaterial comprises AgO. In another instance, the silver materialcomprises Ag₂O. In other embodiments, the silver material comprises adopant wherein the dopant comprises vanadium, niobium, tantalum, iron,tungsten, ruthenium, manganese, molybdenum, any oxide thereof, anyhydroxide thereof, or any combination thereof. For example, the silvermaterial comprises a dopant wherein the dopant comprises vanadium,niobium, any oxide thereof, any hydroxide thereof, or any combinationthereof. In another example, the silver material comprises a dopantwherein the dopant comprises niobium, tantalum, any oxide thereof, anyhydroxide thereof, or any combination thereof.

In other embodiments, the cathode, the anode, or both comprise a binder.For example, in some cells, the cathode comprises a binder. Forinstance, the cathode comprises a binder and the binder comprises PTFEor PVDF. In other examples, the anode comprises a binder. For instance,the anode comprises a binder, and the binder comprises PTFE or PVDF.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.01mol % to about 10 mol % (e.g., from about 0.10 mol % to about 5 mol %,from about 0.25 mol % to about 2.5 mol %, or from about 1 mol % to about8 mol %) of a high valence dopant by weight of doped silver powder; ananode comprising zinc; and an electrolyte comprising KOH.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.10mol % to about 10 mol % of at least one pentavalent dopant by weight ofthe doped silver powder; an anode comprising zinc; and an electrolytecomprising KOH.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.01mol % to about 10 mol % (e.g., from about 0.10 mol % to about 5 mol %,from about 0.25 mol % to about 2.5 mol %, or from about 1 mol % to about8 mol %) of a dopant; an anode comprising zinc; and an electrolytecomprising KOH, wherein the dopant comprises vanadium, niobium,tantalum, any oxide thereof, any hydroxide thereof, or any combinationthereof.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.01mol % to about 10 mol % (e.g., from about 0.10 mol % to about 5 mol %,from about 0.25 mol % to about 2.5 mol %, or from about 1 mol % to about8 mol %) of a dopant; an anode comprising zinc; and an electrolytecomprising KOH, wherein the dopant comprises vanadium, niobium, anyoxide thereof, any hydroxide thereof, or any combination thereof.

Another aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder comprising from about 0.01mol % to about 10 mol % (e.g., from about 0.10 mol % to about 5 mol %,from about 0.25 mol % to about 2.5 mol %, or from about 1 mol % to about8 mol %) of a dopant; an anode comprising zinc; and an electrolytecomprising KOH, wherein the dopant comprises iron, tungsten, ruthenium,manganese, molybdenum, any oxide thereof, any hydroxide thereof, or anycombination thereof.

In some embodiments of these aspects, the silver material comprises apowder. For example, silver material comprises a powder, and the powderhas a mean particle diameter of about 15 μm or less. In other instances,the powder has a mean particle diameter of about 5 μm or less. In somecathodes of these aspects, the silver powder comprises Ag, AgO, Ag₂O,Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK,AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄,hydrates thereof, or any combination thereof. For instance, the silverpowder comprises AgO, Ag₂O, Ag₂O₃, or any combination thereof. In otherinstances, the silver material comprises AgO. And, in some instances,the silver material comprises Ag₂O.

In other embodiments of these aspects, the cathode, the anode, or bothcomprise a binder. For instance, the cathode comprises a binder. Inother instances, cathode comprises a binder, and the binder comprisesPTFE or PVDF. In some instances, the anode comprises a binder. Forinstance, the anode comprises a binder, and the binder comprises PTFE orPVDF.

In other embodiments of these aspects, the cell further comprises anelectrolyte comprising LiOH, NaOH, KOH, RbOH, SrOH or a combinationthereof.

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising silver powder and a first binder; and ananode comprising zinc and a second binder, wherein the doped silverpowder comprises a sufficient amount of vanadium, niobium, tantalum,iron, tungsten, ruthenium, manganese, molybdenum, or any combinationthereof to impart the cathode with a resistivity of about 50 Ohm·cm orless.

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising doped silver powder and a first binder;and an anode comprising zinc and a second binder, wherein the dopedsilver powder comprises a sufficient amount of vanadium, niobium,tantalum, iron, tungsten, ruthenium, manganese, molybdenum, or anycombination thereof to impart the cathode with a resistivity of about 30Ohm·cm or less.

It is noted that any of the cathodes described herein are suitable foruse in electrochemical cells of the present invention.

In one embodiment, the electrochemical comprises an electrolytecomprising LiOH, NaOH or KOH.

In another embodiment, the electrochemical cell comprises a cathodecomprising doped silver oxide powder comprising from about 0.25 mol % toabout 10 mol % of a dopant comprising niobium, vandium, or tantalum orany a combination thereof and a first binder; an anode comprising zincand a second binder; and an electrolyte comprising KOH, wherein thecathode has a resistivity of about 30 Ohm·cm or less.

One aspect of the present invention provides an electrochemical cellcomprising a cathode comprising doped silver powder and a first binder;and an anode comprising zinc and a second binder, wherein the dopedsilver powder comprises a sufficient amount of niobium to impart thecathode with a resistivity of about 30 Ohm·cm or less.

It is noted that any of the cathodes described herein are suitable foruse in electrochemical cells of the present invention.

In one embodiment, the electrochemical comprises an electrolytecomprising LiOH, NaOH, KOH or any combination thereof.

In another embodiment, the electrochemical cell comprises a cathodecomprising doped silver powder comprising from about 0.01 mol % to about10 mol % of a dopant comprising iron, tungsten, ruthenium, manganese,nickel, molybdenum, or any combination thereof and a first binder; ananode comprising zinc and a second binder; and an electrolyte comprisingKOH, wherein the cathode has a resistivity of about 30 Ohm·cm or less.

A. Electrodes

Cathodes and anodes of electrochemical cells of the present inventioncan optionally include additives such as a binder, a current collector,or the like. The binder of the cathode and the binder of the anode caninclude the same material or different materials. In one example, thebinder of the anode or the cathode comprises PTFE, PVDF, or anycopolymer thereof.

In cathodes comprising a binder, the binder is admixed with the dopedsilver powder in a suitable concentration (e.g., less than 10 wt % ofbinder by weight of the cathode, (e.g., 5 wt % or less of binder byweight of the cathode)) and formed into dough-like material that isshaped to provide the cathode with a suitable size and geometry. It isnoted that anodes may likewise be produced using a binder.

B. Separators

Electrochemical cells of the present invention additionally comprise aseparator that is separates the anode from the cathode.

Separators of the present invention can comprise a film having a singlelayer or a plurality of layers, wherein the plurality of layers maycomprise a single polymer (or copolymer) or more than one polymer (orcopolymer).

In several embodiments, the separators comprise a unitary structureformed from at least two strata. The separator can include stratawherein each layer comprises the same material, or each layer comprisesa different layer, or the strata are layered to provide layers of thesame material and at least on layer of another material. In severalembodiments, one stratum comprises an oxidation-resistant material, andthe remaining stratum comprises a dendrite-resistant material. In otherembodiments, at least one stratum comprises an oxidation-resistantmaterial, or at least one stratum comprises a dendrite-resistantmaterial. The unitary structure is formed when the material comprisingone stratum (e.g., an oxidation-resistant material) is coextruded withthe material comprising another stratum (e.g., a dendrite-resistantmaterial or oxidation-resistant material). In several embodiments, theunitary separator is formed from the coextrusion of oxidation-resistantmaterial with dendrite-resistant material.

In several embodiments, the oxidation-resistant material comprises apolyether polymer mixture and the dendrite resistant material comprisesa polyvinyl alcohol (PVA) polymer mixture.

It is noted that separators useful in electrochemical cells can beconfigured in any suitable way such that the separator is substantiallyinert in the presence of the anode, cathode and electrolyte of theelectrochemical cell. For example, a separator for a rectangular batteryelectrode may be in the form of a sheet or film comparable in size orslightly larger than the electrode, and may simply be placed on theelectrode or may be sealed around the edges. The edges of the separatormay be sealed to the electrode, an electrode current collector, abattery case, or another separator sheet or film on the backside of theelectrode via an adhesive sealant, a gasket, or fusion (heat sealing) ofthe separator or another material. The separator may also be in the formof a sheet or film wrapped and folded around the electrode to form asingle layer (front and back), an overlapping layer, or multiple layers.For a cylindrical battery, the separator may be spirally wound with theelectrodes in a jelly-roll configuration. Typically, the separator isincluded in an electrode stack comprising a plurality of separators. Theoxidation-resistant separator of the invention may be incorporated in abattery in any suitable configuration.

1. Polyether Polymer Material

In several embodiments of the present invention the oxidation-resistantstratum of the separator comprises a polyether polymer material that iscoextruded with a dendrite-resistant material. The polyether materialcan comprise polyethylene oxide (PEO) or polypropylene oxide (PPO), or acopolymer or a mixture thereof. The polyether material may also becopolymerized or mixed with one or more other polymer materials,polyethylene, polypropylene and/or polytetrafluoroethylene (PTFE), forexample. In some embodiments, the PE material is capable of forming afree-standing polyether film when extruded alone, or can form afree-standing film when coextruded with a dendrite-resistant material.Furthermore, the polyether material is substantially inert in thealkaline battery electrolyte and in the presence of silver ions.

In alternative embodiments, the oxidation resistant material comprises aPE mixture that optionally includes zirconium oxide powder. Withoutintending to be limited by theory, it is theorized that the zirconiumoxide powder inhibits silver ion transport by forming a surface complexwith silver ions. The term “zirconium oxide” encompasses any oxide ofzirconium, including zirconium dioxide and yttria-stabilized zirconiumoxide. The zirconium oxide powder is dispersed throughout the PEmaterial so as to provide a substantially uniform silver complexationand a uniform barrier to transport of silver ions. In severalembodiments, the average particle size of the zirconium oxide powder isin the range from about 1 nm to about 5000 nm, e.g., from about 5 nm toabout 100 nm.

In other embodiments, the oxidation-resistant material further comprisesan optional conductivity enhancer. The conductivity enhancer cancomprise an inorganic compound, potassium titanate, for example, or anorganic material. Titanates of other alkali metals than potassium may beused. Suitable organic conductivity enhancing materials include organicsulfonates and carboxylates. Such organic compounds of sulfonic andcarboxylic acids, which may be used singly or in combination, comprise awide range of polymer materials that may include salts formed with awide variety of electropositive cations, K⁺, Na⁺, Li⁺, Pb⁺², Ag⁺, NH4⁺,Ba⁺², Sr⁺², Mg⁺², Ca⁺² or anilinium, for example. These compounds alsoinclude commercial perfluorinated sulfonic acid polymer materials,Nafion® and Flemion®, for example. The conductivity enhancer may includea sulfonate or carboxylate copolymer, with polyvinyl alcohol, forexample, or a polymer having a 2-acrylamido-2-methyl propanyl as afunctional group. A combination of one or more conductivity enhancingmaterials can be used.

Oxidation-resistant material that is coextruded to form a separator ofthe present invention can comprise from about 5 wt % to about 95 wt %(e.g., from about 20 wt % to about 60 wt %, or from about 30 wt % toabout 50 wt %) of zirconium oxide and/or conductivity enhancer by weightof the separator. In some embodiments, the zirconium oxide comprises asmall amount (e.g., less than 5 mol %) of yttria (i.e., yttrium oxide).

Oxidation-resistant materials can also comprise additives such assurfactants that improve dispersion of the zirconium oxide powder bypreventing agglomeration of small particles. Any suitable surfactant maybe used, including one or more anionic, cationic, non-ionic, ampholytic,amphoteric and zwitterionic surfactants, and mixtures thereof. In oneembodiment, the separator comprises an anionic surfactant. For example,the separator comprises an anionic surfactant, and the anionicsurfactant comprises a salt of sulfate, a salt of sulfonate, a salt ofcarboxylate, or a salt of sarcosinate. One useful surfactant comprisesp-(1,1,3,3-tetramethylbutyl)-phenyl ether, which is commerciallyavailable under the trade name Triton X-100 from Rohm and Haas.

In several embodiments, the oxidation-resistant material comprises fromabout 0.01 wt % to about 1 wt % of surfactant.

2. Polyvinyl Polymer Material

In several embodiments of the present invention the dendrite-resistantstratum of the separator comprises a polyvinyl alcohol (PVA) polymermaterial that is coextruded with the oxidation-resistant material. Inseveral embodiments, the PVA material comprises a cross-linked polyvinylalcohol polymer and a cross-linking agent.

In several embodiments, the cross-linked polyvinyl alcohol polymer is acopolymer. For example, the cross-linked PVA polymer is a copolymercomprising a first monomer, PVA, and a second monomer. In someinstances, the PVA polymer is a copolymer comprising at least 60 molepercent of PVA and a second monomer. In other examples, the secondmonomer comprises vinyl acetate, ethylene, vinyl butyral, or anycombination thereof.

PVA material useful in separators of the present invention also comprisea cross-linking agent in a sufficient quantity as to render theseparator substantially insoluble in water. In several embodiments, thecross-linking agent used in the separators of the present inventioncomprises a monoaldehyde (e.g., formaldehyde or glyoxilic acid);aliphatic, furyl or aryl dialdehydes (e.g., glutaraldehyde, 2,6furyldialdehyde or terephthaldehyde); dicarboxylic acids (e.g., oxalicacid or succinic acid); polyisocyanates; methylolmelamine; copolymers ofstyrene and maleic anhydride; germaic acid and its salts; boroncompounds (e.g., boron oxide, boric acid or its salts; or metaboric acidor its salts); or salts of copper, zinc, aluminum or titanium. Forexample, the cross-linking agent comprises boric acid.

In another embodiment, the PVA material optionally comprises zirconiumoxide powder. In several embodiments, the PVA material comprises fromabout 1 wt % to about 99 wt % (e.g., from about 2 wt % to about 98 wt %,from about 20 wt % to about 60 wt %, or from about 30 wt % to about 50wt %).

In many embodiments, the dendrite-resistant strata of the separator ofthe present invention comprises a reduced ionic conductivity. Forexample, in several embodiments, the separator comprises an ionicresistance of less than about 20 mΩ/cm², (e.g., less than about 10mΩ/cm², less than about 5 mΩ/cm², or less than about 4 mΩ/cm²).

The PVA material that forms the dendrite-resistant stratum of theseparator of the present invention can optionally comprise any suitableadditives such as a conductivity enhancer, a surfactant, a plasticizer,or the like.

In some embodiments, the PVA material further comprises a conductivityenhancer. For example, the PVA material comprises a cross-linkedpolyvinyl alcohol polymer, a zirconium oxide powder, and a conductivityenhancer. The conductivity enhancer comprises a copolymer of polyvinylalcohol and a hydroxyl-conducting polymer. Suitable hydroxyl-conductingpolymers have functional groups that facilitate migration of hydroxylions. In some examples, the hydroxyl-conducting polymer comprisespolyacrylate, polylactone, polysulfonate, polycarboxylate, polysulfate,polysarconate, polyamide, polyamidosulfonate, or any combinationthereof. A solution containing a copolymer of a polyvinyl alcohol and apolylactone is sold commercially under the trade name Vytek® polymer byCelanese, Inc. In several examples, the separator comprises from about 1wt % to about 10 wt % of conductivity enhancer.

In other embodiments, the PVA material further comprises a surfactant.For example, the separator comprises a cross-linked polyvinyl alcoholpolymer, a zirconium oxide powder, and a surfactant. The surfactantcomprises one or more surfactants selected from an anionic surfactant, acationic surfactant, a nonionic surfactant, an ampholytic surfactant, anamphoteric surfactant, and a zwitterionic surfactant. Such surfactantsare commercially available. In several examples, the PVA materialcomprises from about 0.01 wt % to about 1 wt % of surfactant.

In several embodiments, the dendrite-resistant stratum further comprisesa plasticizer. For example, the dendrite-resistant stratum comprises across-linked polyvinyl alcohol polymer, a zirconium oxide powder, and aplasticizer. The plasticizer comprises one or more plasticizers selectedfrom glycerin, low-molecular-weight polyethylene glycols, aminoalcohols,polypropylene glycols, 1,3 pentanediol branched analogs, 1,3pentanediol, and/or water. For example, the plasticizer comprisesgreater than about 1 wt % of glycerin, low-molecular-weight polyethyleneglycols, aminoalcohols, polypropylene glycols, 1,3 pentanediol branchedanalogs, 1,3 pentanediol, or any combination thereof, and less than 99wt % of water. In other examples, the plasticizer comprises from about 1wt % to about 10 wt % of glycerin, low-molecular-weight polyethyleneglycols, aminoalcohols, polypropylene glycols, 1,3 pentanediol branchedanalogs, 1,3 pentanediol, or any combination thereof, and from about 99wt % to about 90 wt % of water.

In some embodiments, the separator of the present invention furthercomprises a plasticizer. In other examples, the plasticizer comprisesglycerin, a low-molecular-weight polyethylene glycol, an aminoalcohol, apolypropylene glycols, a 1,3 pentanediol branched analog, 1,3pentanediol, or combinations thereof, and/or water.

C. Electrolytes

Electrochemical cells of the present invention can comprise any suitableelectrolyte. For example, the electrochemical cell comprises anelectrolyte that includes aqueous NaOH or KOH. In other examples, theelectrolyte comprises a mixture of LiOH, RbOH, NaOH or KOH and a liquidPEO polymer.

Electrolytes that are suited to electrochemical cells of the presentinvention include an alkaline agent. Example electrolytes includeaqueous metal-hydroxides such as aq. NaOH and/or aq. KOH, orcombinations thereof. Other example electrolytes include aqueousmixtures of metal hydroxide and a polymer that has a glass transitiontemperature below the range of operating and/or storage temperatures forthe electrochemical cell into which it employed (e.g. at least −20° C.).

In one embodiment, the electrolyte comprises PEG, such as mPEG. In someembodiments, the PEG polymer has a molecular weight or mean molecularweight of less than about 10,000 amu (e.g., less than about 5000 amu, orfrom about 100 amu to about 1000 amu).

Alkaline agents useful in the electrolyte of the present invention arecapable of producing hydroxyl ions when mixed with an aqueous or polarsolvent such as water and/or a liquid polymer.

In some embodiments, the alkaline agent comprises LiOH, NaOH, KOH, CsOH,RbOH, or combinations thereof. For example, the alkaline agent comprisesLiOH, NaOH, KOH, or combinations thereof. In another example, thealkaline agent comprises KOH.

In several example embodiments, the electrolyte of the present inventioncomprises more than about 1 wt % of alkaline agent (e.g., more thanabout 5 wt % of alkaline agent, or from about 5 wt % to about 76 wt % ofalkaline agent). In one example, the electrolyte comprises a liquidpolymer comprising PEG and 3 wt % or more (e.g., 4 wt % or more, fromabout 4 wt % to about 33 wt %, or from about 5 wt % to about 15 wt %) ofan alkaline agent. For instance, the electrolyte comprises PEG and 5 wt% or more of KOH. In another example, the electrolyte consistsessentially of water, PEG (e.g., mPEG) having a molecular weight or meanmolecular weight from about 100 amu to about 1000 amu, and 5 wt % ormore of KOH.

In several embodiments, the electrolyte comprises greater than 60 wt %of water by weight of the electrolyte. Additionally, electrolytes of thepresent invention may optionally comprise less than about 10 wt % byweight of electrolyte (e.g., less than about 5 mol % by weight ofelectrolyte or less than about 1 mol % by weight of electrolyte) of asmall carbon chain alcohol such as methanol, ethanol, isopropanol, ormixtures thereof.

In some examples, the electrolyte is aqueous KOH. For instance, 8M KOH,12M KOH, or the like.

In other examples, the electrolyte is aqueous NaOH. For instance, 8MNaOH, 12M NaOH, or the like.

D. Cell Housing

Cells of the present invention can include any suitable housing suchthat the housing does not substantially impede electrical access to theterminals of the cell. In some embodiments, the cell housing comprisesflexible packaging material. Usually, the flexible packaging material isused in a sachet configuration or a drawn cavity configuration. Unliketraditional applications of flexible packaging battery packagingrequires feed through to carry the current from the enclosedelectrochemical cell. Insulating and sealing these feed-throughs can bedone by a number of methods. Typically, the flexible packaging materialconsists of three functional layers, which can be embodied in threephysical layer or less (e.g., in some packaging materials, the physicallayers perform one, two, or three of the functions performed byfunctional layers). The first functional layer is anelectrolyte-compatible layer. This layer provides chemical resistanceand physical containment of the liquid or gelatinous electrolyte.Typically this layer can consist of a polyolefin or polyethylvinylalcohol that may be co-extruded or mixed with an adhesion promoter,ethyl acrylic acid for example, to facilitate heat sealing or currentfeed-through adhesion. The second functional layer is a vapor barrierlayer. This layer can be a metal, aluminum, or a low transmissibilitypolymer. This functional layer needs to retard the diffusion of water,electrolyte solvent, oxygen, hydrogen, and carbon dioxide into or out ofthe cell. The third functional layer provides a physical integrity layeron the outside of the packaging. It provides much of the packagingmaterial's strength and abrasion resistance. This layer may also providethe physical strength to allow the packaging material to be formed intoblisters. This layer is typically nylon or mylar in its composition. Thefunctional layer materials can also be applied as conformal coatings tothe cells by dip coating or spraying. Cells packaged in flexiblepackaging typically contain a reduced pressure atmosphere with theabsolute pressure inside less than ambient pressure.

V. EXAMPLES:

The following materials may be used to produce example cathodes, testcathodes, and/or example electrochemical cells of the present invention:

Example No. 1 Doped AgO

The following materials and methods were used to generate doped AgOcathode material that was used in test cells for purposes of generatingcomparative data concerning cell performance characteristics, i.e., cellcycle life.

Materials:

-   -   Silver nitrate: A.C.S. grade, DFG    -   Gelatin: from bovine skin, type B, ˜225 bloom, Sigma    -   Potassium hydroxide solution: KOH solution, 1.4 g/ml, LabChem.,        Inc.    -   Potassium persulfate, 99+%, Sigma-Aldrich

In a 4 L glass reactor, added AgNO₃ (431.8 g) to H₂O (1000 g) at 55° C.while stirring with an overhead mechanical stirrer at 400 rpm. Thenadded a H₂O (200 g) suspension of three nano-materials: SiO₂ (48 mg),ZnO (89 mg), and ZrO₂ (444 mg). After adding high valence earlytransition metal dopant (see Table 1), Gelatin (0.26 g) was then addedto the stirred solution. After allowing to stir at 55° C. for 10 min, amixture of 40% wt KOH (962 g, aq.) and H₂O (962 g) was pumped in at arate of 96.2 g/min using size 16 master-flex tubing for 20 min. Thetemperature of the glass reactor was then increased to 65° C. K₂S₂O₈(527.5 g) was then added to the reactor all at once immediately uponreaching 65° C. The reaction was allowed to stir at 65° C. for 50 min.Upon cooling, the solution was decanted away and the solid blackparticles were then washed with H₂O (4 L×13) until the conductivity ofthe wash was less than 20 μS.

TABLE 1 List of weights to make 315 g of the high valence earlytransition metal doped AgO cathode materials and physical properties ofbatches synthesized. Resistivity D50 Particle BET Surface Dopant Weight(g) Activity (%) (Ωcm) Size (μm) Area (m²/g) Nb₂O₅ 3.4124 95.1 2.3181.48 2.3168 KMnO₄ 4.0577 97.0 2.174 8.52 + KReO₄ 7.4281 94.6 2.083 1.252.2696 V₂O₅ 2.3350 95.0 1.886 1.37 2.6666 Ta₂O₅ 5.6731 94.8 1.946 1.81 +WO₃ 5.9527 97.2 2.086 1.38 + MoO₃ 3.6956 96.7 1.955 1.23 + CrO₃ 2.567494.5 2.089 1.30 + MnO₂ 2.2322 95.7 2.013 1.20 2.6028 ReS₂ 6.4277 93.51.872 1.48 + Fe(NO₃)₃•9H₂O 10.8849 + + + + Fe₂O₃ 4.3025 + + + +

Note that in Table 1, entries having marked with “+” indicate that datawas not available for use in this application.

Example No. 2 Coating of Doped AgO

An H₂O (3459.5 g) solution of doped AgO (314.5 g) was stirred at 550 rpmwith an overhead stirrer in a 4 L flask. A solution of Pb(CH₃CO₂)₂.3H₂O(12.265 g) in H₂O (200 g) was then pumped into the flask at a rate of3.33 g/min using size 14 master-flex tubing for 60 min at roomtemperature. Upon completion of the addition, the solution was decantedaway from the black solid which was then rinse with H₂O (4 L×13) untilthe conductivity of the wash was less than 20 μS. The black precipitatewas then collected via filtration and then dried overnight under vacuumat 60° C.

Example No. 3 Undoped AgO

A 2 L glass reactor was placed into a hot water bath and a Teflon-coatedradial propeller was used. A total of 116.7 g of AgNO₃ and 1000 g of DIwater were added to the reactor and stirred at 400 rpm. The mixture inthe reactor was heated to 55° C. 0.11 g gelatin was added.

In a plastic container, 240 g of KOH solution (1.4 g/ml) was mixed with240 g DI water to give a diluted KOH solution. The diluted KOH solutionwas added to the reactor per pump at 55° C. At 65° C., 198 g ofpotassium persulfate was added and the temperature was maintained for 50min.

The water was decanted as the solution cooled down and the particlessettled. The particles were rinsed with DI water, and once the particlessettled, the water was decanted. The particles underwent this rinse anddecant process until the ion conductivity of the mixture measured below25 micro-Ohm. The product was filtered and dried in a 60° C. vacuumoven.

The resultant undoped AgO cathode material is characterized below inTable 2.

TABLE 2 Undoped AgO cathodes. Cathode Resistivity Particle Size (μm)Formulation Activity (Ohm · cm) D10 D50 D95 Undoped AgO >95 24 0.41 1.443.4

The activity of cathode materials described in Tables 1 and 2 wasmeasured by titration:

A sample was crushed with a spatula. If sample was not completely dry,it was dried in a vacuum oven at 60° C. overnight. A total of 0.100 g ofsample was added to a clean 125 ml flask, wherein the weight wasmeasured accurately to at least the third decimal place. Next, 10 ml ofacetate buffer and 5 ml KI solution was added to the flask. The flaskwas swirled to disperse particles followed by covering the flask byputting an inverted plastic cup over top, and sonicating for 2 hours.Next, 20 ml of DI was added to the flask. The solution was titrated withNa₂S₂O₃ until the solution achieved a pale yellow (record exactnormality). Approximately 1 ml of starch indicator was added andtitration continued until the solution achieved a milky whitish-yellowendpoint.

The following equation was used to calculate activity:

${Activity} = \frac{\left( {{{vol}.\mspace{14mu} {titrant}}\mspace{14mu} ({mls})} \right) \times \left( {{normally}\mspace{14mu} {titrant}} \right) \times 12.388}{\left( {{mass}\mspace{14mu} {of}\mspace{14mu} {silver}\mspace{14mu} {material}\mspace{14mu} (g)} \right)}$

Particle size analysis was performed using a Horiba LA-930. Diameters on10%, 50%, and 95% (D10, D50, and D95) were measured for the samplesprovided above and below.

The resistivities of this cathode materials were measured using thefollowing procedure: 3 grams of sample material was loaded into a powdercompression cell with a 3.88 cm² electrode surface area. Force wasapplied to the sample from 10 to 40 tons by using a laboratory hydraulicpress. The resistance was recorded every 5 tons and the thickness of thesample at 40 tons is also recorded. The resistivity of the sample is theresistance value extrapolated to infinite force divided by finalmaterial thickness and multiplied by the area of the powder cellelectrodes.

Example No. 4 Cathode Preparation

Referring to FIGS. 2-11, test cells for evaluating the properties of thedoped silver materials in cathodes were manufactured as follows:

A PTFE emulsion (6.4% wt in H₂O, DuPont) was sprayed on to dry AgO (73g) and mixed thoroughly and then fibrillated with a Speed Mixer (DAC 150FVZ, FlackTek Inc). The wet AgO dough was rolled out to a thickness of(2 mm) before being placed into an oven at 60° C. and dried in vacuo forthree hours. The dried AgO cathode dough was additionally rolled down toa thickness of 0.9 mm and cut into 15.5 mm diameter disks.

Example No. 5 Test Cells

Using standard 2032 coin cell components (lid, can, gasket, and crimpring), the cathode disk was placed into the 2032 can while a Zn/ZnOanode consisting of 85.0% wt Zn, 13.0% wt ZnO, 0.5% wt Bi₂O₅, and 1.5%wt PTFE was placed into the 2032 lid. The porous electrodes were thenfilled with electrolyte utilizing an Audionvac VMS 43 (−0.9 bar). Astack of standard battery separators consisting of porous polyethyleneand cellophane were placed in between the two electrodes and the batterywas crimped shut and tested for the absence of leaks and a stable opencircuit voltage. A MACCOR battery tester was then used to cycle theassemble AgO cathode at a constant current rate of C/5 with a limit of2.0V during charge and 1.4V during discharge. Electrolyte: 32% by weightaqueous KOH and NaOH mixture (80/20 mol ratio).

Other Embodiments

All publications and patents referred to in this disclosure areincorporated herein by reference to the same extent as if eachindividual publication or patent application were specifically andindividually indicated to be incorporated by reference. Should themeaning of the terms in any of the patents or publications incorporatedby reference conflict with the meaning of the terms used in thisdisclosure, the meaning of the terms in this disclosure are intended tobe controlling. Furthermore, the foregoing discussion discloses anddescribes merely example embodiments of the present invention. Oneskilled in the art will readily recognize from such discussion and fromthe accompanying drawings and claims, that various changes,modifications and variations can be made therein without departing fromthe spirit and scope of the invention as defined in the followingclaims.

1. A cathode for use in an electrochemical cell comprising a silvermaterial that is doped with a high valence dopant to give a doped silvermaterial, wherein the dopant is present in a concentration of from about0.01 mol % to about 10 mol %.
 2. (canceled)
 3. (canceled)
 4. The cathodeof claim 1, wherein the doped silver material comprises a powder.
 5. Thecathode of claim 4, wherein the powder has a mean particle diameter ofabout 20 μm or less.
 6. (canceled)
 7. The cathode of claim 5, whereinthe silver material comprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH,AgONa, AgOK, AgOLi, AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂,AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃, Ag₄FeO₄, or any combinationthereof.
 8. (canceled)
 9. (canceled)
 10. (canceled)
 11. The cathode ofclaim 1, wherein the high valence dopant comprises Nb, Mn, Re, V, Ta, W,Mo, Cr, Fe, or any combination thereof.
 12. The cathode of claim 11,wherein the high valence dopant comprises an oxide or a hydroxide of Nb,Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.
 13. Thecathode of claim 11, wherein the high valence dopant comprises anacetate, a formate, a sulfide, a sulfate, a nitrate, a nitride, anamide, a hydroxide, a perchlorate, a phosphate, a triflate, a silicide,a carbonate, or a carbonyl of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or anycombination thereof.
 14. The cathode of claim 11, wherein the highvalence dopant comprises a salt of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, orany combination thereof.
 15. The cathode of claim 11, wherein the highvalence dopant comprises Nb₂O₅, KMnO₄, KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃,CrO₃, MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O, or any combination thereof.16-28. (canceled)
 29. A method of producing a cathode for use in anelectrochemical cell comprising providing a silver powder that is dopedwith from about 0.01 mol % to about 10 mol % of at lease one highvalence dopant; and forming the doped silver powder into a cathode. 30.(canceled)
 31. (canceled)
 32. The method of claim 29, wherein the dopedsilver powder has a mean particle diameter of about 15 μm or less. 33.(canceled)
 34. The method of claim 32, wherein the doped silver powdercomprises Ag, AgO, Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi,AgORb, AgOONa, AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂,FeO₃, Ag₂FeO₃, Ag₄FeO₄, or any combination thereof.
 35. (canceled) 36.(canceled)
 37. (canceled)
 38. The method of claim 34, wherein the dopantcomprises Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.39. The method of claim 38, wherein the dopant comprises an oxide or ahydroxide of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combinationthereof.
 40. The method of claim 38, wherein the dopant comprises anacetate, a formate, a sulfide, a sulfate, a nitrate, a nitride, anamide, a hydroxide, a perchlorate, a phosphate, a triflate, a silicide,a carbonate, or a carbonyl of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or anycombination thereof.
 41. The method of claim 38, wherein the dopantcomprises a salt of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combinationthereof.
 42. The method of claim 38, wherein the dopant comprises Nb₂O₅,KMnO₄, KReO₄, V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂, Fe₂O₃,Fe(NO₃)₃.9H₂O, or any combination thereof.
 43. An electrochemical cellcomprising a cathode comprising a silver material comprising a dopant;and an anode comprising zinc, wherein the dopant comprises a highvalence dopant, and the dopant is present in a sufficient concentrationto impart the cell with an actual capacity of at least about 60% of thecell's rated capacity over at least about 50 charge cycles. 44.(canceled)
 45. (canceled)
 46. The cell of claim 43, wherein the silvermaterial comprises from about 0.01 mol % to about 10 mol % of at leastone high valence dopant.
 47. The cell of claim 46, wherein the silvermaterial comprises a powder.
 48. The cell of claim 47, wherein thepowder has a mean particle diameter of about 20 μm or less. 49-54.(canceled)
 55. The cell of claim 48, further comprising an electrolytecomprising LiOH, NaOH, KOH, RbOH, or a combination thereof.
 56. The cellof claim 55, wherein the silver material further comprises Ag, AgO,Ag₂O, Ag₂O₃, Ag₃O₄, AgOH, AgOOH, AgONa, AgOK, AgOLi, AgORb, AgOONa,AgOOK, AgOOLi, AgOORb, AgCuO₂, AgFeO₂, AgMnO₂, Ag(OH)₂, FeO₃, Ag₂FeO₃,Ag₄FeO₄, or any combination thereof.
 57. (canceled)
 58. (canceled) 59.(canceled)
 60. The cell of claim 43, wherein the dopant comprises Nb,Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.
 61. The cellof claim 60, wherein the dopant comprises an oxide or a hydroxide of Nb,Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.
 62. The cellof claim 60, wherein the dopant comprises an acetate, a formate, asulfide, a sulfate, a nitrate, a nitride, an amide, a hydroxide, aperchlorate, a phosphate, a triflate, a silicide, a carbonate, or acarbonyl of Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combinationthereof.
 63. The cell of claim 60, wherein the dopant comprises a saltof Nb, Mn, Re, V, Ta, W, Mo, Cr, Fe, or any combination thereof.
 64. Thecell of claim 60, wherein the dopant comprises Nb₂O₅, KMnO₄, KReO₄,V₂O₅, Ta₂O₅, WO₃, MoO₃, CrO₃, MnO₂, ReS₂, Fe₂O₃, Fe(NO₃)₃.9H₂O, or anycombination thereof. 65-82. (canceled)